Just quick:

I have (2x^4)+(4x^3)-(5x^2)-5x+2.

The only possible rational roots by the Rational Root Test are 1,-1,2,-2,.5,-.5.

The only one that works out of these is -1. Could someone just check this for me?

Jimmy

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- Oct 22nd 2006, 08:10 AMJimmyTRational Roots
Just quick:

I have (2x^4)+(4x^3)-(5x^2)-5x+2.

The only possible rational roots by the Rational Root Test are 1,-1,2,-2,.5,-.5.

The only one that works out of these is -1. Could someone just check this for me?

Jimmy - Oct 22nd 2006, 08:29 AMtopsquark
I agree. Good work!

You can always check these by division as well. You should be able to divide $\displaystyle 2x^4+4x^3-5x^2-5x+2$ by x - (-1) either by long or synthetic division to find:

$\displaystyle 2x^4+4x^3-5x^2-5x+2 = (x+1)(2x^3+2x^2-7x+2)$

confirming that there is no remainder.

-Dan